Fourth-generation head of engineering giant Bechtel Corp., firm that built Hoover Dam and Chunnel. Father, Stephen, became president 1960, chairman 1973. Riley started as mechanic's helper at age 14; still has first Bechtel paycheck. Chairman and chief executive in 1990. Sales up 32% to $27 billion in 2007; firm booked $34 billion in new work last year. New jobs include a 1,600-megawatt, coal-fired power plant in Illinois and a liquefied natural gas processing plant in Angola. Completed U.K.'s first high-speed rail line and Tacoma Narrows Bridge near Seattle earlier this year. Believed to still have stake in privately held money management firm Fremont Group.